Coverings For Viscoelastic Foam Mattresses

ABSTRACT

Covers for mattresses having a reclining surface of viscoelastic foam have a fabric body with a first surface disposed in engagement with the reclining surface; an opposite, second surface disposed for engagement by a person reclining upon the cover; and at least one air flow region defined by the fabric body for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. The circular knit fabric body comprises a flame retardant material.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is a continuation-in-part of, and claims priority under 35 U.S.C. §120 from U.S. application Ser. No. 12/162,516, filed Jul. 29, 2008, which is a National Stage of PCT Application PCT/US2007/060974, filed on Jan. 24, 2007, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application 60/764,612, filed on Feb. 2, 2006. The disclosures of these prior applications are considered part of the disclosure of this application and are incorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to viscoelastic foam mattresses and fabric coverings for such mattresses.

BACKGROUND

A trend in the mattress market is the use of viscoelastic foams, also referred to as “memory foams” or foams having compressible memory to form a sleeper-supporting surface. Viscoelastic foam conforms to the shape of an object resting upon its surface, and regains its generally flat surface once the object is removed. These foams, described, for example, in U.S. Pat. No. 6,734,220, the entire disclosure of which is incorporated by reference herein, are generally formed of cured polyurethane-based viscoelastic polymer. Viscoelastic mattresses are often covered with a fabric cover, typically made of a fabric referred to as “ticking”

SUMMARY

In various aspects, the disclosure features covers for mattresses having a reclining surface of viscoelastic foam. The disclosure provides mattress covers having both flame retardant properties and enhanced air circulation under a reclined person. A mattress cover exhibit both of these properties is possible by including a flame retardant material in the stitch or pile yarn of the fabric used in constructing the mattress cover. Each flame retardant mattress cover prevents flame break-through to the underlying mattress, thus eliminating the need for a separate flame barrier between the mattress and the cover.

In one aspect, the cover comprises a circular knit fabric body having four-way stretch and defining: (a) a first pile surface disposed in engagement with the reclining surface; (b) an opposite, second pile surface disposed for engagement by a person reclining upon the cover with the first surface disposed in engagement with the reclining surface; and (c) at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. The circular knit fabric body includes a flame retardant material.

In some implementations, the circular knit fabric body includes a stitch yarn comprising the flame retardant material as flame retardant fiber(s). In some examples, the stitch yarn is a blend of natural fiber (e.g., cotton or wool) and the flame retardant fiber. The stitch yarn forms a fiber barrier that inhibits flames from passing across the circular knit fabric body from the second pile surface toward the mattress. In some examples, the stitch yarn is a blend of natural fiber and the flame retardant fiber. In some examples, the stitch yarn is a blend of a non-flame retardant fiber and the flame retardant fiber. In addition, the flame retardant fiber can include at least one of the following fibers: fiber containing silicate; melamine resin; carbon fiber; and fiberglass. The flame retardant fiber has a limited oxygen index (LOI) of at least 25. In some examples, the flame retardant fiber is included in the pile/velour yarn as well as the stitch yarn. In some implementations, the flame retardant material is selected from the group consisting of m-aramid, modacrylic, flame retardant Rayon, flame retardant polyester, p-aramid, Polybenzimidazole (PBI), and blends thereof. The circular knit fabric body may include a stitch yarn containing between about 3% and about 10% flame retardant material, such as fiberglass, p-aramid or PBI. In some implementations, the circular knit fabric body includes a pile yarn comprising flame retardant fiber. For example, the pile yarn can include flame retardant fiber blended with an other, non-flame retardant fiber. In some cases, the flame retardant material includes flame retardant fiber(s) blended with an other, non-flame retardant fiber. The flame retardant material can include a flame retardant fiber formed of inherent flame retardant material (e.g., m-aramid, modacrylic, flame retardant rayon, Polybenzimidazol, flame retardant polyester, and/or p-aramid).

In some implementations, at least one of the first pile surface and the second pile surface defines one or more regions with relatively high pile disposed among one or more regions of relatively low pile or no pile, with the one or more regions of relatively low pile or no pile defining the one or more air flow regions for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. Some of these implementations include one or more of the following features. The one or more regions with relatively high pile and the one or more regions of relatively low pile or no pile are arranged upon at least one of the first pile surface and the second pile surface by engineered body mapping techniques in a manner to position the one or more air flow regions for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover in accordance with requirements of corresponding body regions of the person reclining upon the cover. The one or more regions with relatively high pile and the one or more regions of relatively low pile or no pile are arranged upon at least one of the first pile surface and the second pile surface by standard knitting design techniques in a manner to position the one or more air flow regions for enhanced circulation of air generally between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover in a regular pattern. Contrasting height among regions of relatively high pile and regions of relatively low pile or no pile is established by contrasting height of sinker loops. The sinker loops are in unnapped yarn form; in napped, velour form; or in cut loop form without pre-napping. The fabric body comprises a fabric laminate. The fabric body comprises stretch stitch yarns, e.g., stitch yarns with spandex. The fabric body comprises hydrophilic fibers. The fabric body comprises fibers of synthetic material, e.g., selected from the group consisting of polyester, acrylic, nylon, these fibers rendered hydrophilic, and blends thereof. The fabric body comprises material selected from the group consisting of cotton and wool. The fabric body includes cellulosic fibers (e.g., natural cellulosic fibers, such as cotton, or synthetic cellulosic fibers, such as lyocell fibers). The fabric body has chemical treatment for one or more properties selected from the group consisting of wicking enhancement, stain release, water repellency, stain repellency, antimicrobial properties, and oil repellency. In some implementations, the fabric body comprises a double bar raschel warp knit construction.

In some implementations, the one or more regions of relatively high pile comprises a plurality of spaced-apart pile pillars and the one or more regions of relatively low pile or no pile comprises intersecting channels extending among the pile pillars and defining the one or more air flow regions for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. In some of these implementations, the fabric body comprises a knit structure with about 16 to about 28 wales per inch and about 14 to about 36 courses per inch. The fabric body has fineness in a range of about 40 to about 600 denier, with individual fibers having fineness in a range of about 1 dpf to about 12 dpf.

In another aspect, the cover comprises a fabric body defining (a) a first surface disposed in engagement with the reclining surface; (b) an opposite, second surface disposed for engagement by a person reclining upon the cover; and (c) at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. The circular knit fabric body includes a flame retardant material.

In some implementations, the flame retardant material is selected from the group consisting of m-aramid, modacrylic, flame retardant Rayon, flame retardant polyester, p-aramid, Polybenzimidazole (PBI), and blends thereof. The circular knit fabric body may include a stitch yarn having a blend of a natural yarn and the flame retardant material. In some examples, the circular knit fabric body includes a stitch yarn containing between about 3% and about 10% flame retardant material, such as fiberglass, p-aramid or PBI.

In some implementations, the fabric body comprises a first fabric layer defining the first surface and a second fabric layer defining the opposite, second surface, with the one or more air flow regions defined therebetween; and the fabric body further comprises a plurality of intermediate members extending generally between the first fabric layer and the second fabric layer and through the one or more air flow regions for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. Some of these implementations include one or more of the following features. The plurality of intermediate members are disposed to resiliently urge apart the first fabric layer and the second fabric layer. The first fabric layer is permeable to water vapor and impermeable to liquid water. Each of the first fabric layer and the second fabric layer comprises stitch yarn. The stitch yarn of the first fabric layer has fineness in a range of about 50 to about 600 denier. The stitch yarn of the first fabric layer is a spun yarn that has an overall denier in a range of about 50 to about 600 denier. The stitch yarn of the first fabric layer has individual fiber fineness in the range of about 0.3 to about 6.0 dpf. The stitch yarn of the first fabric layer comprises hydrophilic fibers. The stitch yarn of the first fabric layer comprises a synthetic material, e.g., selected from the group consisting of polyester, acrylic, nylon, these fibers rendered hydrophilic, and blends thereof. The stitch yarn of the second fabric layer comprises natural fibers. The stitch yarn of the second fabric layer comprises material selected from the group consisting of cotton and wool. The second fabric layer further comprises lay-in yarn held by the stitch yarn, e.g., an elastomeric yarn. The lay-in yarn comprises total fineness in a range of about 70 to about 300 denier.

The disclosure also features methods for forming a cover for a mattress having a reclining surface of viscoelastic foam.

For example, in one aspect, the disclosure features a method including (a) forming a circular knit fabric having four way stretch, with a first pile surface and an opposite, second pile surface and defining at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover; and (b) forming the circular knit fabric into a cover for a mattress having a reclining surface of viscoelastic foam. The circular knit fabric body includes a flame retardant material.

In a further aspect, the disclosure features covers for a mattress having a reclining surface of viscoelastic foam, the cover formed by the above methods.

The term “pile,” as used herein, includes pile surfaces formed by any desired method, including but not limited to cut loops, loops cut on the knitting machine, loops cut off the knitting machine, and raised fibers.

Some implementations exhibit one or more of the following advantages. The fabric cover conforms generally to the surface of the viscoelastic foam mattress as the foam changes in configuration from its original flat form to a conforming, compressed state and back to the original flat form. The cover provides minimum restriction to movement of the foam, so there is less tendency for the foam to bulge and/or crease. The fabric cover is comfortable to the user. Preferred mattress covers define one or more regions of air circulation between the viscoelastic foam surface of the mattress and the opposed skin surface of a person sleeping on the mattress, so that even as the viscoelastic foam conforms closely to the shape of the person sleeping on the mattress, the cover permits circulation of air between the surface of the mattress and the person's skin, to allow the person to sleep comfortably, including during warmer conditions.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a mattress cover on a mattress having a viscoelastic foam surface layer, with a sleeping person reclining upon the mattress surface.

FIG. 2 is a perspective view of a mattress cover according to one implementation, in which a raised upper surface and/or a raised lower surface of the cover defines one or more air flow regions for enhanced circulation of air between a sleeping person and the viscoelastic surface of the mattress.

FIG. 2A is a highly enlarged partial perspective view of area A-A in FIG. 2.

FIG. 3 is a sectional view of a mattress cover according to another implementation, in which a raised upper surface and/or a raised lower surface has one or more regions of relatively high pile among one or more regions of relatively low or no pile, the regions of relatively low or no pile defining one or more air flow regions for enhanced circulation of air between a sleeping person and the viscoelastic surface of the mattress. In this implementation, the regions are arranged according to engineered body mapping techniques to accommodate corresponding body regions of a sleeping person.

FIG. 4 is a perspective view of a mattress cover according to another implementation, similar to the implementation of FIG. 3, in which a raised upper surface and/or a raised lower surface has one or more regions of relatively high pile among regions of relatively low or no pile, the regions of relatively low or no pile defining air flow regions for enhanced circulation of air between a sleeping person and the viscoelastic surface of the mattress, the regions in this implementation being evenly spread in an overall pattern according to standard knitting design techniques.

FIG. 5 is a sectional view of a mattress cover according to another implementation of the disclosure, in which pile pillars extending from upper and/or lower surfaces of the cover define air flow regions for enhanced circulation of air between a sleeping person and the viscoelastic surface of the mattress.

FIG. 6 is a sectional view of a mattress cover according to a further implementation of the disclosure, in which intermediate members span air flow regions defined between the upper surface and the lower surface of the mattress cover for enhanced circulation of air between a sleeping person and the viscoelastic surface of the mattress.

FIG. 7 is a perspective view of a mattress cover in which the smooth, technical face surface of two fabric layers are adhered together face-to-face to form a two-layer laminate, with their respective outer, technical back surfaces facing outward.

FIG. 8 is a perspective view of the mattress cover of FIG. 3.

FIG. 9 is a perspective view of the mattress cover of FIG. 5.

FIG. 10 is a perspective view of the mattress cover of FIG. 6.

FIG. 11 is a side elevational view showing loop structure of a two-layer, three dimensional fabric suitable for use in the mattress cover shown in FIGS. 6 and 10.

FIG. 12 is a side elevational view showing a larger area of the fabric of FIG. 11.

FIG. 13 is a perspective view of the fabric of FIG. 12 viewed from its technical back and illustrating formation of sinker loops.

FIG. 14 is a front elevational view of the fabric of FIG. 12 viewed from its technical face.

FIG. 15 is a side view showing terry loops of the fabric construction of FIG. 12 prior to (a) napping on the technical face and (b) shearing on the technical back.

FIG. 16 is a side view of terry loops on the technical face of the fabric construction of FIG. 15 after napping.

FIG. 17 is a side view of terry loops on the technical back of the fabric construction of FIG. 16 after shearing.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The present disclosure features a mattress cover that provides good air circulation under a person reclined on the mattress cover while also inhibiting break through of flames through the fabric of the mattress cover into the underlying foam of the mattress covered by the mattress cover. In preferred examples, the mattress cover provides both flame retardant properties and enhanced air circulation under a reclined person, thus eliminating the need for a separate flame barrier between the mattress and the cover.

A mattress 100 having a viscoelastic foam surface layer 101 with a cover 102 is shown diagrammatically in FIG. 1. The mattress cover 102 is formed of a knitted fabric having at least two-way stretch with good recovery, e.g., a circular knit or warp knit fabric. The fabric typically includes spandex yarn, to allow the knitted fabric to conform to deformation of the compressed viscoelastic foam in multiple directions under load, and to avoid restricting recovery of the viscoelastic foam when the load is removed or reduced. Preferably the fabric has four-way balanced stretch, i.e., the elongation when the fabric is subjected to a load is substantially the same along the length and width of the fabric. The mattress cover is constructed to define one or more air flow regions for enhanced circulation of air between the reclining surface of viscoelastic foam and skin surfaces of a person reclining upon the cover. The regions for enhanced circulation of air may be provided in various forms. As will be described in further detail below, the stitch yarn of the knitted fabric exhibits flame retardant properties to prevent or retard a flame from breaking through the mattress cover to an underlying mattress.

Referring to FIG. 2, in one implementation, the fabric 211 forming mattress cover 102 includes raised surfaces 105, 107 on its technical face and technical back. As indicated by the arrow in FIG. 2A, these raised surfaces, formed of pile or loops, allow air flow between the pile fibers or loops. Thus, the raised surfaces provide enhanced circulation of air. Preferably, the fabric 211 is a circular knit fabric having four way stretch.

In another implementation, for example, as shown in FIGS. 3 and 8, the fabric 211′ forming mattress cover 102′″ has a raised surface with a three-dimensional geometry in which one or both surfaces define a predetermined pattern of regions of no loops or low loops or pile and regions of relatively higher loops or pile. The regions of relatively higher pile 110 are positioned and constructed to support the person reclining upon the cover and spaced from the reclining surface of viscoelastic foam, with regions of low pile and no pile 112 defining air flow regions for enhanced circulation of air through the air flow regions, between the reclining surface, F, of viscoelastic foam and the skin surface, S, of the person reclining upon the cover 102′″. In some cases, the fabric 211′ is an engineered thermal fabric with regions of contrasting cushioning and air-flow capacity and performance, arranged by body mapping concepts, tailored to the different requirements of different regions of the sleeper's body. Greater cushioning will be provided by the regions 110 of relatively higher loops, reducing pressure on regions of the body that tend to compress the mattress more, e.g., hips and shoulders. Moreover, air ventilation will occur in the no loop or low loop regions 112 disposed among the regions 110 of relatively higher loops, thereby increasing the comfort level by reducing perspiration and heat build-up. Thus, such fabrics 211′ will tend to optimize the comfort level of the person while sleeping. The distribution of the low and high pile areas can be selected to suit particular conditions and user preferences, and different products can be provided having different distributions.

The high and low pile areas may be distributed in a regular pattern, for example in bands, to simplify manufacture. As shown in FIG. 4, a lower band region 220 having relatively higher pile height and/or relatively higher fiber density may be positioned to extend generally across the person's hips and an upper band region 222, also of relatively higher pile height and/or relatively higher fiber density, may be positioned to extend generally across the person's shoulders. At the upper and lower extremities, respectively, of the mattress cover, a top region 224 of relatively low pile or no pile is positioned to extend generally beneath the person's head and along the side wall at the head of the mattress and a bottom band region 226 of relatively low pile or no pile is positioned to extend along the side wall at the foot of the mattress. An intermediate region 228, also of relatively low pile or no pile, is positioned to extend generally across the person's upper torso.

In another implementation, for example, as shown in FIGS. 5 and 9, a fabric 111 forming a mattress cover 102″ has a raised surface on the technical back and a velour or terry sinker loop surface on the technical face. The raised surface on the technical back, disposed to face the viscoelastic foam surface layer 101, defines gaps or channels 104 allowing movement of air along the surface of the fabric, e.g., between the surface, F, of the mattress and the skin surface of the person reclining on the mattress. The velour or terry loop on the technical face of the fabric disposed to face the skin, S, of the reclining person, similarly defines gaps or channels to allow air circulation between the skin surface of the person's body and the viscoelastic surface of the mattress. The surface of raised pile fabric 111 defines spaced-apart pile pillars 103 among intersecting channels 104 defined therebetween. The pile pillars may be found at one surface of the fabric, or at both surfaces (technical face and technical back) of the fabric, e.g., as shown in FIGS. 5 and 9. The pile pillars define air flow regions, allowing enhanced circulation of air between the reclining surface, F, of the viscoelastic foam and the skin surface, S, of a person reclining upon the cover 102″. The channels will also enhance moisture evaporation. The channels 104 may have any desired configuration; for example the channels may be in discrete regions of the fabric which may be interconnected or not interconnected, or may be continuous from one edge of the fabric to the opposite edge.

In another implementation, shown in FIGS. 6 and 10, a fabric body 11 forming a mattress cover 102′ has the form of a two-layer, spacer fabric having an air circulation space defined between layers. In some example, the fabric 11 has a three-dimensional double knit fabric including a first layer 13 and a second layer 15 that are spaced apart resiliently by interconnecting yarns 21. Such fabrics will be discussed in detail below. The resilient interconnecting yarns 21 urge the first layer 13 and second layer 15 apart, including under the weight of the reclining person, to permit air flow passageways 22 between the two layers, and thus between the surface, F, of the viscoelastic foam mattress and the surface, S, of a reclining person's skin. Air circulating through these air flow passageways 22 assists in cooling, and in removal of perspiration or other moisture, by evaporation.

In the implementations shown in FIGS. 2, 3 and 5, the fabric may be a two-layer laminate, with the smooth, technical face surface of the respective fabric layers being adhered together face-to-face and the respective outer, technical back surfaces (carrying the raised surfaces of FIG. 2, the regions of high pile and low pile of FIG. 3, or the pile pillars of FIG. 5) facing outward at both surfaces. For example, referring to FIG. 7, laminate 300 includes two fabrics 302, 304, the smooth surfaces of which are adhered together at an interface 306. Each fabric carries a raised pile area 308, 310 on its technical back surface 312, 314.

In some implementations, the fabric includes stitch yarn, pile/velour yarn, or fibers that include a flame retardant material, such as m-aramid yarn or fibers, as sold by E.I. duPont de Nemours and Company, Inc. under the trademarks NOMEX® and KEVLAR®, modacrylic, flame retardant Rayon, flame retardant polyester, p-aramid, Polybenzimidazole (PBI) fiber and/or polymer, as sold by PBI Performance Products, Inc., and/or other suitable flame retardant materials. Preferably, the flame retardant fibers have a limited oxygen index (LOI) of at least 25. In some examples, the flame retardant yarns/fibers are blended with natural yarn or fibers formed, e.g., of cotton or wool. The flame retardant yarns/fibers need to maintain their physical strength during exposure to a flame, so as not to let the flame break through the textile fabric and gain access to the mattress foam. The stitch yarn (which holds the whole knit construction together) provides a fire and heat barrier that prevents a flame from reaching a foam mattress covered by the mattress cover 102. The stitch yarn should maintain its integrity when exposed to high heat (e.g., over 500° C.) for a long period of time and experience relatively low weight loss. For example, using ASTM E 1590-07 Standard Test Method for Fire Testing of Mattresses, the contents of which is hereby incorporated by reference in its entirety, to test the flame retardance of the mattress cover 102 on a mattress 100, the stitch yarn should maintain its integrity when exposed to flames of a gas burner for 180 seconds at a flow rate of 12 L/min, determined a pressure of 101±5 kPa and a temperature of 20±5° C. A hospital mattress covered by the cover 102 should experience a loss of mass of less than 5 kg. Examples of flame retardant fibers that can be included in the stitch yarn include, but not are limited to: cellulosic fiber containing silicate (e.g., Visil by Kuito in Finland), melamine resin (e.g., Basofil by Basofil Fibers in Enka, N.C.), carbon fibers (e.g., Pyron by Zoltek in Bridgeton, Mo.), and fiberglass (e.g. available from Dow Corning Corp.). Each of these fibers, separately or in combination, can be blended with other flame retardant fibers (e.g. p-Aramid, m-Aramid, etc.). A yarn/fiber blend containing between about 3% and about 10% of a suitable flame retardant material, such as p-aramid, PBI, or fiberglass can employed to minimize flame break through.

In some examples, the loop/pile includes a meltable fiber, such as polyester, which further enhance the resistance to a flame break through. The meltable fiber, which is held together with the stitch construction, will melt and stick together with the stitch to generate a matrix resistant to flame break through. Spandex and/or Lycra may be included in the stitch to improve the synergy between the knit mattress cover and a memory foam mattress. The flame retardant yarns/fibers may be included in each of the fabrics disclosed herein, to provide a mattress cover 102 having flame retardant properties to prevent flame break through to an underlying mattress.

The fabrics discussed above with reference to FIGS. 3-6 will now be discussed in further detail. The flame retardant properties and characteristics of the fabrics discussed above can be incorporated in each of the examples described below.

Fabrics Having a Pattern of High and Low/No Pile Regions

In the engineered knit fabrics 211′ discussed above with reference to FIGS. 3 and 8, the various regions can have pile of predetermined fiber density and predetermined pile height. The contrast of cushioning and airflow may be achieved, for example, by forming regions of different pile heights (e.g., using different sinker heights), different pile densities (e.g., using full face velour and velour with pattern of pile and no pile), and/or different types of yarns (e.g., using flat yarns with low shrinkage and texture yarns with high shrinkage). Regions of selected shape and size can be arranged in predetermined desired pattern, tailored, as discussed above, for use by persons of different ages and different genders, etc. and for other factors, such as seasonality, etc.

The surfaces of regions of relatively high pile height may be, for example, plain velour. Typically, the yarn and the pile density is maintained constant for all regions, again for simplicity of manufacture. The three dimensional pattern may exist on one or both sides of the fabric. For example, if the fabric is formed by a reverse plaiting process, the three dimensional pattern will exist on both sides of the fabric, typically, in register.

The engineered thermal fabric articles can be produced by any procedure suitable for creating regions of contrasting pile heights and/or regions with no pile, in predetermined designs. Examples of suitable procedures include electronic needle and/or sinker selection; tubular circular or terry loop knit construction, e.g. by reverse plaiting, to form double face fleece or to form pseudo single face fabric, or by regular plaiting, to form single face fleece; warp knit construction; woven construction; and fully fashion knit construction. In some implementations, the engineered thermal fabrics have a circular knit reverse plaited construction which is suitable for generating a single or double face surface fabric.

To simplify manufacturing, in some implementations, e.g., as shown in FIG. 4 and discussed above, the regions of contrasting performance are arranged in band form, extending across the mattress cover.

Any suitable yarn or fibers may be employed in forming the engineered thermal fabrics. Examples of suitable yarn or fibers include synthetic yarn or fibers formed, e.g., of polyester, nylon or acrylic; natural yarn or fibers formed, e.g., of cotton or wool; regenerate yarn or fibers, such as rayon; and specialty yarn or fibers, such as aramid yarn or fibers, as sold by E.I. duPont de Nemours and Company, Inc. under the trademarks NOMEX® and KEVLAR®.

Fabrics Having Pile Pillars

Referring to FIGS. 5 and 14, the raised surface fabric 111 discussed above includes a plurality of courses of loop yarn 113 integrated with stitch or backing yarn 115. The manner in which pile pillars are formed in this fabric will be discussed in detail below.

First, loop yarn 113 is plaited around stitch yarn 115 in order to define a plurality of fabric loops 114 (FIG. 15). Fabric 111 has a circular knit reverse plaited construction suitable for generating a two-face-surface fabric, as described below.

Once fabric 111 is formed, technical face 117 is napped or otherwise raised (FIG. 16). The napping process is carried out in a manner to maintain full loop coverage with minimal distortion of technical back 119. In particular, during the napping process, the integrity of loop yarn 113 on technical back 119 may, to some extent, be compromised, as it is pulled shorter, due to the napping process. Accordingly, loop yarn 113 generally must be knit longer, e.g. utilizing sinker loops of at least 2.0 mm or greater, in order to be able to shear loops 114 along technical back 119 at the conclusion of the napping process.

Once the napping or raising process is completed, loops 114 along technical back 119 are sheared, as shown in FIG. 17. Generally, the shearing step takes place after the napping step. If shearing takes place as the first fabric finishing step, as is usual for standard single face cut loop fabrics, the cut loops 114 can be pulled through the back to the face during any subsequent napping process.

The channels between pile pillars may be formed using, for example, the techniques described in U.S. Pat. No. 6,927,182, the complete disclosure of which is incorporated herein by reference. In such techniques, vertical channels are constructed with the use of tipped and tipless sinkers, high and low sinkers, or some combination of both (e.g., 4 tipped sinkers, 2 tipless, 3 tipped sinkers, 2 tipless, repeat; 3 high sinkers, 1 low sinker, 2 high sinkers, 2 low sinkers, repeat; etc.). Horizontal channels may be created by removing the loop yarn from one or more feeds in some arrangement, or with the use of a shrinkable loop yarn which creates a channel after processing with wet (e.g., hot water, steam) or dry (air) heat (e.g., 4 loop in, 2 loop out, 3 loop in, 2 loop out, repeat; 3 low shrinkage loop, 3 high shrinkage loop, 3 low shrinkage loop, 3 high shrinkage loop, repeat; etc.).

Loop yarn 113 generally has bulk greater than that of the stitch yarn 115. For example, loop yarn 113 may have a denier of between about 70 and 600, while stitch yarn 115 has a denier of between about 30 and 150. Loop yarn 113 is preferably formed of 100% polyester or nylon. Loop yarn 113 may also be formed of other materials such as acrylic. Stitch yarn 115 may be formed, e.g., of polyester or nylon. In some implementations, the flame retardant fibers (described earlier) are included in the loop yarn 113 and/or the stitch yarn 115.

The fabric 111 may be knit on a standard terry sinker loop knitting machine or on a jacquard machine, the latter enabling the production of different height fabric loops along the technical back of the fabric.

Two-Layer Fabrics

The two-layer fabrics 11 described above with reference to FIGS. 6 and 10 may be prepared by knitting a three-dimensional knit fabric on a double-needle bar warp knitting machine or circular knitting machine, both of which are well known in the art. As shown in FIGS. 11 and 12, the three-dimensional knit spacer fabric is generally indicated at 11 and includes a first fabric layer 13 formed of stitch yarn 17, a second fabric layer 15 formed of stitch yarn 19, and pile yarn 21 interconnecting the two layers. In addition, knit fabric 11 includes backing or lay-in yarns 25 and 26 (FIG. 11), held by stitch yarns 17 and 19 respectively.

Pile yarns 21 have sufficient resilience and stiffness to space the two fabric layers apart, e.g., including when pressure is applied upon a fabric layer outer surface. The pile yarns 21 extend generally between the first fabric layer 13 and the second fabric layer 15 and through the air flow region therebetween. As discussed above, the resilient separation provided by pile yarns 21 enhances circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover. The pile yarns are spaced and positioned to resiliently urge apart the two fabric layers, thereby maintaining the air flow region to optimize user comfort. Moreover, the pile yarns 21 are sufficiently spaced from one another to allow circulating air flow through the intermediate region of the fabric 11. This enhanced air flow helps to prevent bed sores, which can occur due to constant body pressure and limited air circulation.

Pile yarn 21 may be knit with between 16 and 28 wales per inch and 14 to 36 courses per inch. This density enhances the ability of the fabric to maintain the spacing of the two layers under pressure. Pile yarn 21 may be made of the same material as the two fabric layers, or may be made of a different material. In order to render the interconnecting pile yarn resilient, the yarn may be made of a resilient material such as monofilament or multifilament polyester, nylon, etc. Pile yarn 21 may have a fineness of between 40 and 600 denier, e.g., between 40 and 300 denier, with an individual fiber fineness of 1 to 12 dpf.

The pile yarn may be made from fibers that have been rendered hydrophilic in order to facilitate the transport of moisture from top layer 13 to layer 15. In some implementations, the flame retardant fibers are included in the pile/velour yarn 21. Stitch yarn 17 of top layer 13 is also preferably made of fibers that have been rendered hydrophilic. This construction facilitates moisture transport away from the body, maintaining a comfortable top layer and air circulation next to the skin. The top layer 13 may be chemically treated or it may be formed of modified fibers that render the fabric layer hydrophilic, as described in U.S. Pat. No. 5,312,667, the complete disclosure of which is incorporated herein by reference. The transport of water from the surface is substantially enhanced by the hydrophilic nature of the top layer because liquid moisture is readily transportable along the surface of the yarn fibers of the layer.

Top layer 13 may be formed of stitch yarn having a fineness of between 50 and 600 denier with an individual fiber fineness in the range of between 0.3 and 2.5 dpf, if multifilament. Backing or lay-in yarns 25 and 26 of top layer 13 may be multifilament and may have a fineness of between 70 and 300 denier, with an individual fiber fineness of 0.5 to 5.0 dpf.

The stitch yarns may be formed of synthetic material such as polyester, acrylic or nylon, or in some cases a natural material such as cotton. The yarns may be filament or spun, textured or fully oriented. Preferably, stitch yarns 17 and 19 and backing yarns 25 and 26 are formed of polyester or nylon that has been rendered hydrophilic in order to enhance transport of perspiration or water. In some implementations, the flame retardant fibers are included in the stitch yarn 17.

Second fabric layer 15 may be the same as top layer 13 or may have different characteristics. Layer 15 may in some cases consist of hygroscopic fibers in order to absorb and hold a considerable volume of moisture. Particularly, backing yarn 26 of second fabric layer 15 may be formed of moisture absorbent material such as cotton (which absorbs 2 to 3 times its weight of water), rayon, wool or a super absorbent fiber such as a hydrolyzed copolymer of acrylic acid (which absorbs between two and eight times its weight). In accordance with the disclosure, any suitable moisture absorbent material may be used, e.g., natural fibers or synthetics, so long as the yarn or fiber material chosen for layer 15 has relatively greater moisture absorbency than the fiber or yarn of layer 13. In some implementations, the flame retardant fibers are included in the backing yarn 26.

The use of a super absorbent fiber is quite desirable in that the fibers will absorb many times their own weight, even when under pressure, and will retain the absorbed liquid when subjected to pressure. Examples of suitable types of super absorbent fibers are described in U.S. Pat. No. 5,344,698, the complete disclosure of which is incorporated herein by reference.

If cotton or rayon fibers are used for the second fabric layer, they may be chemically modified after knitting the composite fabric by treatment with alkyl chlorides and cross-linking of the resultant ethers to form carboxymethylated cellulosic fibers, as known to one of skill in the art, in order to render the second layer super absorbent.

The surface of top fabric layer 13 may be sanded, brushed or napped, forming a pile or velour surface. The yarn which is more coarse, i.e. either the stitch yarn or the interconnecting pile yarn, is napped. Generally the yarn napped is a multifilament yarn.

Optionally, as discussed above, the fabric may incorporate elastomeric yarn, such as LYCRA or SPANDEX, in one or both of lay-in yarns 25 and 26 of layers 13 and 15, respectively, and/or the stitch yarns 17, 19. Such yarn will have a total fineness between about 70 and 300 denier. This will enhance softness and flexibility of the layer, and thus its conformability to the viscoelastic foam. The elastomeric yarn may also be added to the stitch yarn of one or both layers.

Top layer 13 may be coated with a breathable barrier layer, i.e., a barrier layer that is impermeable to liquid water but permeable to water vapor. The barrier layer deposited on the fabric layer is preferably a film with good moisture vapor transmission characteristics. Suitable films include polyurethane, polysiloxane and polysulfane.

The barrier layer may be applied to the fabric layer by methods well known in the art. These include transfer coating, in which the barrier layer is first placed or laid on a carrier. Thereafter, the film is placed on the fabric layer, and the carrier is then discarded. Alternative methods for applying the film include direct lamination of an extruded film, as well as direct roller coating of a solution onto the fabric layers from which the solvent is then evaporated. A further method for applying the barrier layer is first applying an adhesive on the fabric layer by spraying or gravure printing and then placing a self-supporting film on top of the adhesive in the manner of lamination.

A portion of the pile yarns 21 interconnecting the two layers may be perpendicular to each of the first and second fabric layers, while the remaining pile yarns 21 are disposed at varying angles between the two layers, with the result that the former will be of lesser and the latter of greater bulk. Such constructions are described in U.S. Pat. No. 6,156,406, the complete disclosure of which is incorporated herein by reference.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, other implementations are within the scope of the following claims. 

1. A cover for a mattress having a reclining surface of viscoelastic foam, the cover comprising: a circular knit fabric body having four-way stretch and defining: a first pile surface disposed in engagement with the reclining surface; an opposite, second pile surface disposed for engagement by a person reclining upon the cover with the first surface disposed in engagement with the reclining surface; and at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover; wherein the circular knit fabric body comprises a flame retardant material.
 2. The cover of claim 1, wherein the circular knit fabric body comprises a stitch yarn including the flame retardant material, the flame retardant material comprising a flame retardant fiber.
 3. The cover of claim 2, wherein the stitch yarn comprises a blend of natural fiber and the flame retardant fiber.
 4. The cover of claim 2, wherein the stitch yarn forms a fire barrier that inhibits flames from passing across the circular knit fabric body from the second pile surface toward the mattress.
 5. The cover of claim 2, wherein the flame retardant fiber comprises at least one of fiber containing silicate, melamine resin, carbon fiber, and fiberglass.
 6. The cover of claim 2, wherein the flame retardant fiber is blended with an other flame retardant fiber.
 7. The cover of claim 6, wherein the other flame retardant fiber is selected from the group consisting of p-aramid, m-aramid, modacrylic, flame retardant Rayon, flame retardant polyester, Polybenzimidazole, and blends thereof.
 8. The cover of claim 1, wherein the fabric body comprises a pile yarn, the pile yarn comprising a flame retardant fiber.
 9. The cover of claim 8, wherein the flame retardant fiber is blended with an other, non-flame retardant fiber.
 10. The cover of claim 1, wherein the flame retardant material comprises a flame retardant fiber formed of inherent flame retardant material.
 11. The cover of claim 1, wherein the flame retardant material comprises yarns comprising flame retardant fiber formed of inherent flame retardant material blended with an other, non-flame retardant fiber.
 12. The cover of claim 1, wherein the circular knit fabric body has chemical treatment for one or more properties selected from the group consisting of wicking enhancement, stain release, water repellency, stain repellency, antimicrobial properties, and oil repellency.
 13. The cover of claim 12, wherein the fabric body comprises hydrophilic fibers.
 14. The cover of claim 1, wherein the fabric body comprises a fabric laminate.
 15. The cover of claim 1, wherein at least one of the first pile surface and the second pile surface defines one or more regions with relatively high pile disposed among one or more regions of relatively low pile or no pile, with the one or more regions of relatively low pile or no pile defining the at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover.
 16. The cover of claim 15, wherein the one or more regions with relatively high pile and the one or more regions of relatively low pile or no pile are arranged upon at least one of the first pile surface and the second pile surface by engineered body mapping techniques in a manner to position the at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover in accordance with requirements of corresponding body regions of the person reclining upon the cover.
 17. The cover of claim 16, wherein contrasting height among regions of relatively high pile and regions of relatively low pile or no pile is established by contrasting height of sinker loops.
 18. The cover of claim 15, wherein the one or more regions with relatively high pile and the one or more regions of relatively low pile or no pile are arranged upon at least one of the first pile surface and the second pile surface by standard knitting design techniques in a manner to position the at least one air flow region for enhanced circulation of air generally between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover in a regular pattern.
 19. The cover of claim 18, wherein contrasting height among regions of relatively high pile and regions of relatively low pile or no pile is established by contrasting height of sinker loops.
 20. The cover of claim 19, wherein the circular knit fabric body comprises stitch yarn with spandex.
 21. The cover of claim 19, wherein the circular knit fabric body comprises stretch stitch yarn.
 22. The cover of claim 19, wherein the sinker loops of the at least one of the first pile surface and the second pile surface are in un-napped yarn form.
 23. The cover of claim 19, wherein the sinker loops of the at least one of the first pile surface and the second pile surface are in napped, velour form.
 24. The cover of claim 19, wherein the sinker loops of the at least one of the first pile surface and the second pile surface are in cut loop form without pre-napping.
 25. The cover of claim 19, wherein the circular knit fabric body comprises hydrophilic fibers.
 26. The cover of claim 19, wherein the circular knit fabric body comprises material selected from the group consisting of cotton and wool.
 27. The cover of claim 1, wherein the circular knit fabric body comprises cellulosic fibers.
 28. The cover of claim 19, wherein the circular knit fabric body comprises fibers of synthetic material.
 29. The cover of claim 28, wherein the synthetic material is selected from the group consisting of polyester; nylon; acrylic; polyester, nylon or acrylic that has been rendered hydrophilic; and blends thereof.
 30. The cover of claim 15, wherein the one or more regions of relatively high pile comprises a plurality of spaced-apart pile pillars and the one or more regions of relatively low pile or no pile comprises intersecting channels extending among the pile pillars and defining the at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover.
 31. The cover of claim 30, wherein the fabric body comprises a double bar raschel warp knit construction.
 32. The cover of claim 30, wherein the fabric body comprises a knit with about 16 to about 28 wales per inch.
 33. The cover of claim 30, wherein the fabric body comprises a knit structure with about 14 courses to about 36 courses per inch.
 34. The cover of claim 30, wherein yarns of the fabric body have fineness in a range of about 40 to about 600 denier.
 35. The cover of claim 30, wherein yarns of the fabric body comprise individual fibers having fineness in a range of about 1 dpf to about 12 dpf.
 36. A cover for a mattress having a reclining surface of viscoelastic foam, the cover comprising: a fabric body defining: a first surface disposed in engagement with the reclining surface; an opposite, second surface disposed for engagement by a person reclining upon the cover; and at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover; wherein the circular knit fabric body comprises a flame retardant material.
 37. The cover of claim 36, wherein the circular knit fabric body comprises a stitch yarn including the flame retardant material, the flame retardant material comprising a flame retardant fiber.
 38. The cover of claim 37, wherein the stitch yarn comprises a blend of natural fiber and the flame retardant fiber.
 39. The cover of claim 37, wherein the flame retardant fiber comprises at least one of cellulosic fiber containing silicate, melamine resin, carbon fiber, and fiberglass.
 40. The cover of claim 37, wherein the flame retardant fiber is blended with an other flame retardant fiber.
 41. The cover of claim 40, wherein the other flame retardant fiber is selected from the group consisting of p-aramid, m-aramid, modacrylic, flame retardant Rayon, flame retardant polyester, Polybenzimidazole, and blends thereof.
 42. The cover of claim 36, wherein the fabric body comprises a pile yarn, the pile yarn comprising a flame retardant fiber.
 43. The cover of claim 42, wherein the flame retardant fiber is blended with an other, non-flame retardant fiber.
 44. The cover of claim 36, wherein the fabric body comprises a pile yarn, the pile yarn comprising a non-flame retardant fiber.
 45. The cover of claim 36, wherein the flame retardant material is selected from the group consisting of m-aramid, modacrylic, flame retardant Rayon, flame retardant polyester, p-aramid, Polybenzimidazole, and blends thereof.
 46. The cover of claim 36, wherein the fabric body comprises a first fabric layer defining the first surface and a second fabric layer defining the opposite, second surface, with the at least one air flow region defined therebetween; and the fabric body further comprises a plurality of intermediate members extending generally between the first fabric layer and the second fabric layer and through the at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover.
 47. The cover of claim 46, wherein the plurality of intermediate members are disposed to resiliently urge apart the first fabric layer and the second fabric layer.
 48. The cover of claim 46, wherein the first fabric layer is permeable to water vapor and impermeable to liquid water.
 49. The cover of claim 46, wherein each of the first fabric layer and the second fabric layer comprises stitch yarn.
 50. The cover of claim 49, wherein the stitch yarn of the first fabric layer has fineness in a range of about 50 to about 600 denier.
 51. The cover of claim 49, wherein the stitch yarn is a spun yarn having an overall denier in the range of about 50 denier to about 600 denier.
 52. The cover of claim 49, wherein the stitch yarn of the first fabric layer has individual fiber fineness in the range of about 0.3 to about 6.0 dpf.
 53. The cover of claim 49, wherein the stitch yarn of the first fabric layer comprises hydrophilic fibers.
 54. The cover of claim 49, wherein the stitch yarn of the first fabric layer comprises fibers of synthetic material.
 55. The cover of claim 54, wherein the synthetic material is selected from the group consisting of polyester; acrylic; nylon; polyester, acrylic or nylon that has been rendered hydrophilic; and blends thereof.
 56. The cover of claim 49, wherein the stitch yarn of the second fabric layer comprises natural fibers.
 57. The cover of claim 56, wherein the stitch yarn of the second fabric layer comprises material selected from the group consisting of cotton and wool.
 58. The cover of claim 49, wherein the second fabric layer further comprises lay-in yarn held by the stitch yarn.
 59. The cover of claim 58, wherein the lay-in yarn comprises an elastomeric yarn.
 60. The cover of claim 59, wherein the lay-in yarn comprises total fineness in a range of about 70 to about 300 denier.
 61. A method of forming a cover for a mattress having a reclining surface of viscoelastic foam, the cover, the method comprising the steps of: forming a circular knit fabric having four way stretch, with a first pile surface and an opposite, second pile surface and defining at least one air flow region for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover; and forming the circular knit fabric into a cover for a mattress having a reclining surface of viscoelastic foam; wherein the circular knit fabric body comprises a flame retardant material. 